JP6014528B2 - Fuel cell stack - Google Patents

Description

  Embodiments described herein relate generally to a fuel cell stack.

  The fuel cell stack using a solid polymer electrolyte membrane having proton conductivity as an electrolyte is provided with gas flow passages on both sides of a membrane electrode assembly (MEA) in which the electrolyte membrane is sandwiched between a fuel electrode and an oxidant electrode. A single-cell battery is configured by arranging an electrically conductive separator, and both ends of a laminate in which a plurality of single-cell batteries are stacked are held by end plates, and a plurality of studs are passed through holes that penetrate both end plates, and springs are formed. It is comprised by fastening a laminated body via.

  It is necessary to uniformly supply fuel (hydrogen) and oxidant (air) necessary for the reaction and cooling water necessary for cooling to each single cell battery of such a fuel cell stack. A manifold is provided for distributing and recovering water to the fuel cell stack.

  There are two types of manifolds in the fuel cell stack: an internal manifold system and an external manifold system. In the external manifold system, the gas flow path provided in the separator is extended to the end of the separator and opened to the side of the stack, and separated. The external manifold is arranged on both side surfaces of the laminate, and the reaction gas and cooling water are circulated through them.

  Thus, in the external manifold system, since the separator does not include a manifold, the separator has the same size as the effective area of the membrane electrode assembly, and the separator can be made compact, which is advantageous for cost reduction. Further, since it is possible to use an inexpensive insulating plastic for the external manifold, the cost increase can be minimized. In addition, the volume of the manifold can be set without being restricted by the size of the separator, and gas and cooling water can be evenly distributed to the gas / cooling water flow passages of each single cell battery constituting the laminate. It is.

Japanese Patent No. 3444484

  In the external manifold system, it is necessary to seal so that liquid (cooling water) and gas (fuel gas, oxidant gas) do not leak from between the manifold and the side of the laminate. For example, a sealing member is disposed between the portion and the side surface of the laminated body. However, there is an area outside the seal member at the corner of the laminate, in which liquid and gas are sealed between the manifold and the laminate and between the cells that make up the laminate. It is only shut off and the seal is insufficient. That is, in this region, the leakage of liquid and gas during the power generation operation can be suppressed within a certain allowable value, but, for example, when water is held in the battery stack for a long time, the water pressure and osmotic force cause a minute amount. There is a problem that water leaks.

  In particular, in a configuration in which the battery stack is purged with water to prevent deterioration and the gas inlet / outlet control valve is simplified, the battery stack needs to be disposed in the lower side in the package of the fuel cell system. It is necessary to suppress the leak to zero.

  The problem to be solved by the present invention is to provide a fuel cell stack having a seal structure of an external manifold that can prevent not only liquid and gas during operation but also minute oozing of water in the battery stack during stopped storage. It is to provide.

According to the embodiment, the first electrode has a membrane electrode assembly in which a solid polymer electrolyte membrane is sandwiched between first and second gas diffusion electrodes, and a fuel gas flow passage in contact with the first gas diffusion electrode. A laminate comprising a plurality of unit cells each including a separator and a second separator having an oxidant gas flow passage in contact with the second gas diffusion electrode, and the fuel gas flow passage of the laminate is opened. A fuel gas external manifold that is disposed on a side surface and communicates with the fuel gas flow passage, and an oxidant gas exterior that is disposed on a side surface where the oxidant gas flow passage of the laminate is open and communicates with the oxidant gas flow passage. comprising a manifold, and the fuel gas external manifolds and the stack is sealed by the first sealing member fuel gas outer manifold side and the oxidizing gas outer manifold and the laminate It sealed by the first sealing member oxidant gas external manifold side, wherein the adjacent fuel gas outer manifold and the oxidant gas external manifold is sealed by the second sealing member.

It is a top view which shows the internal structure of the polymer electrolyte fuel cell which concerns on 1st Embodiment. It is A-A 'sectional drawing of the fuel cell stack which comprises the polymer electrolyte fuel cell shown in FIG. It is a figure explaining the effect | action of the seal | sticker of a manifold seal part. It is a figure which expands and shows the manifold seal part of the polymer electrolyte fuel cell shown in FIG. It is a top view which shows the internal structure of the polymer electrolyte fuel cell which concerns on 2nd Embodiment. It is a figure which expands and shows the manifold seal part of the polymer electrolyte fuel cell shown in FIG. It is a figure which expands and shows the manifold seal part of the polymer electrolyte fuel cell which concerns on 3rd Embodiment. It is a figure which expands and shows the manifold seal part of the polymer electrolyte fuel cell which concerns on 3rd Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a top view showing the internal structure of the polymer electrolyte fuel cell according to the first embodiment, and FIG. 2 is an AA view of a fuel cell stack 10 constituting the polymer electrolyte fuel cell shown in FIG. 'Cross section. In FIG. 1 and FIG. 2, each single cell battery 11 of the fuel cell stack 10 includes a membrane / electrode assembly (MEA) 12, a fuel separator 13, and an oxidant / cooling water separator 14. A fuel gas flow passage 13 a is provided on the surface of the fuel separator 13, and an end thereof opens to the side surface of the fuel cell stack 10. An oxidant gas flow passage 14 a is provided on one surface of the oxidant / cooling water separator 14, and a cooling water flow passage 14 b is provided on the other surface, and their end portions open to the side surface of the fuel cell stack 10. doing.

  An oxidant gas inlet / cooling water outlet manifold 21, an oxidant gas outlet / cooling water inlet manifold 22, and a fuel gas inlet manifold 31 are provided on the outer side surface of the fuel cell stack 10 formed by stacking a plurality of single cell batteries 11. A fuel gas outlet manifold 32 is arranged. The oxidant gas inlet / cooling water outlet manifold 21 and the oxidant gas outlet / cooling water inlet manifold 22 communicate with the oxidant gas flow passage 14a and the cooling water flow passage 14b, and the fuel gas inlet manifold 31 and the fuel gas outlet manifold 32 are connected to each other. The fuel gas flow passage 13a communicates with the fuel / oxidant gas necessary for the reaction, supplied to the membrane electrode assembly, discharged, and supplied with cooling water at a predetermined flow rate to remove heat generated by the reaction. I do.

  Each of the manifolds 21, 22, 31, and 32 needs to have gas impermeability and electrical insulation, and is usually manufactured by compression molding or injection molding of a thermoplastic resin or a thermosetting resin with a mold. Is done. Examples of the thermoplastic resin used for this include polyphenylene sulfide (PPS), and examples of the thermosetting resin include an epoxy resin and a phenol resin. Each manifold has a box shape with an opening on the side of the laminate, and a taper is provided on the side surface and the inner surface of the manifold from the fuel cell stack 10 side toward the bottom surface of the manifold, thereby releasing the mold from the mold. Is secured.

  A seal groove with a rectangular cross section is provided over the entire periphery of the peripheral edge of the manifold in contact with the side surface of the fuel cell stack 10. A seal material is inserted into the seal groove, thereby preventing leakage of gas / cooling water.

  As shown in FIG. 2, in the membrane / electrode assembly (MEA) 12, an anode catalyst layer 42a and a cathode catalyst layer 43a are disposed on both sides of a polymer electrolyte membrane 41, and gas diffusion layers 42b and 43b are disposed outside them. Arranged. The electrolyte membrane 41 needs to have gas barrier properties as well as ion conductivity, and is extended to the same size as the fuel separator 13 and the oxidant / cooling water separator 14 in order to prevent mixing of the reaction gas.

  The catalyst layers 42 a and 43 a are slightly smaller than the fuel separator 13, the oxidant / cooling water separator 14 and the electrolyte membrane 41, and reactive gas is passed around them (the gap between the separators 13 and 14 and the electrolyte membrane 41). An edge sealing material 51 for sealing is disposed. The edge seal material 51 is disposed at the same position as the end of the gas flow passage. On the other hand, the openings of the fuel gas manifolds 31 and 32 are located at the positions indicated by broken lines, and are located inside the gas flow passage.

  FIG. 3 shows an enlarged view of a manifold seal portion between the fuel cell stack 10 and, for example, an oxidant gas inlet / cooling water outlet manifold 21. A manifold such as an oxidant gas inlet / cooling water outlet manifold 21 is disposed on the outer side surface of the fuel cell stack 10, and a manifold seal 61 is disposed in the seal groove 21 a of the manifold 21. The manifold seal 61 has an O-ring shape with a circular or elliptical cross section, and is manufactured by compression molding or injection molding a rubber material such as silicon rubber, fluorine rubber, ethylene-propylene-diene rubber (EPDM) with a mold.

  FIG. 3A shows a state before a load is applied to the manifold 21. No load is applied to the manifold seal 61, and the cross-sectional shape remains elliptical. The height of the manifold seal 61 (the width of the O-ring) is set larger than the depth of the manifold seal groove 21a. FIG. 3B shows a state after applying a load to the manifold 21. The seal 61 contracts due to the load, and seal pressure is applied to the upper and lower contact surfaces, and the gas / cooling water is reliably sealed.

  As shown in FIG. 1, the seal member including the manifold seal groove and the manifold seal is provided between the side surface of the fuel cell stack 10 and the oxidant gas / cooling water manifolds 21, 22 and the fuel gas manifolds 31, 32. It is also provided between the sealing surfaces of the gas manifolds 31 and 32 and the side surfaces of the oxidant gas / cooling water manifolds 21 and 22. The enlarged view is shown in FIG. As shown in FIG. 4, the seal surface between the fuel gas manifold 31 and the side surface of the fuel cell stack 10 is provided with a seal groove 33a and a seal 62a disposed therein. A seal groove 33b is provided on the seal surface between the agent gas / cooling water manifold 21 and a seal 62b is disposed therein. That is, a first seal member including a seal groove 33 a and a seal 62 a is provided between the fuel gas manifold 31 and the side surface of the fuel cell stack 10, and the fuel gas manifold 31 and the oxidant gas / cooling water manifold 21 are connected to each other. A second seal member including a seal groove 33b and a seal 62b is provided therebetween.

  Between the side surface of the fuel cell stack 10 and the oxidant gas / cooling water manifolds 21 and 22 and the fuel gas manifolds 31 and 32, liquid and gas are allowed by a seal (first seal member) as shown in FIG. Although it is sealed below the value, minute leaks from the corner exposed to the outside of the seal cannot be prevented. On the other hand, a seal groove 33b is also provided between the seal surfaces of the fuel gas manifolds 31 and 32 and the side surfaces of the oxidant gas / cooling water manifolds 21 and 32, and the seal 62b is disposed therein, so that the second By providing the seal member, it is possible to completely prevent a minute leak at the corner portion.

(Second Embodiment)
FIG. 5 is a top view showing the internal structure of the polymer electrolyte fuel cell stack according to the second embodiment. The fuel cell stack shown in FIG. 5 is different from the fuel cell stack according to the first embodiment shown in FIG. 1 only in the manifold seal portion. In the fuel cell stack shown in FIG. 1, the seal surfaces between the fuel gas manifolds 31 and 32 and the side surfaces of the oxidant gas / cooling water manifolds 21 and 22 are the side surfaces of the fuel gas manifolds 31 and 32 and the fuel cell stack 10. Are coplanar with the sealing surface between. On the other hand, in the fuel cell stack shown in FIG. 5, the seal surfaces between the fuel gas manifolds 31 and 32 and the side surfaces of the oxidant gas / cooling water manifolds 21 and 22 are separated from the fuel gas manifolds 31 and 32 and the fuel cell stack. The taper surface is inclined at a predetermined angle with respect to the seal surface between the ten side surfaces.

  An enlarged view of the manifold seal portion of FIG. 5 is shown in FIG. As shown in FIG. 6, the seal between the fuel gas manifolds 31 and 32 and the side surface of the fuel cell stack 10 is the same as the manifold seal portion shown in FIGS. 1 and 4, and a seal groove 33 a is provided. The seal 62a is disposed therein, and the seal surface of the seal between the fuel gas manifolds 31 and 32 and the oxidant gas / cooling water manifolds 21 and 22 is provided between the fuel gas manifolds 31 and 32 and the fuel cell stack 10. The fuel gas manifolds 31 and 32 and the oxidant gas / cooling water manifolds 21 and 22 are in contact with the tapered surfaces with respect to the seal surface between the side surfaces. As shown in FIG. 5, a seal groove 33c is provided on the inclined seal surfaces of the fuel gas manifolds 31 and 32, a seal 62c is disposed therein, and a second seal member is provided.

  Between the side surface of the fuel cell stack 10 and the oxidant gas / cooling water manifolds 21 and 22 and the fuel gas manifolds 31 and 32, liquid and gas are allowed by a seal (first seal member) as shown in FIG. Although it is sealed below the value, minute leaks from the corner exposed to the outside of the seal cannot be prevented. On the other hand, a seal groove 33c is also provided between the seal surfaces of the fuel gas manifolds 31 and 32 and the side surfaces of the oxidant gas / cooling water manifolds 21 and 22, and the seal 62c is disposed therein, so that the second By providing the seal member, it is possible to completely prevent a minute leak at the corner portion.

  The contact surfaces between the fuel gas manifolds 31 and 32 and the oxidant gas / cooling water manifolds 21 and 22 are tapered so that the fuel gas manifolds 31 and 32 and the oxidant gas / cooling water manifolds 21 and 22 are connected. It can be independently attached to the side surface of the fuel cell stack 10, thereby improving the assembly workability.

(Third embodiment)
7 and 8 are enlarged cross-sectional views of the manifold seal portion of the polymer electrolyte fuel cell stack according to the third embodiment. 1 to 6, the seals between the fuel gas manifolds 31 and 32, the oxidant gas / cooling water manifolds 21 and 22, and the side surface of the fuel cell stack 10 are provided as fuel gas manifolds. 31 and 32 and oxidant gas / cooling water manifolds 21 and 22 are provided with seal grooves 23 and 33a, and seals 61 and 62a are disposed therein, which are performed by a first seal member.

  On the other hand, in the example shown in FIG. 7, a seal groove 73a is provided on the side of the fuel cell stack 10 in contact with the oxidant gas / cooling water manifolds 21 and 22, and the seal 61 is disposed therein. In the example shown in FIG. 8, a seal groove 73b is provided on the side of the fuel cell stack 10 in contact with the fuel gas manifolds 31 and 32, and a seal 62a is disposed therein.

  Although not shown, both the seal between the fuel gas manifolds 31 and 32 and the side surface of the fuel cell stack 10 and the seal between the oxidant gas / cooling water manifolds 21 and 22 and the side surface of the fuel cell stack 10 are both shown. It is also possible to provide a seal groove on the fuel cell stack 10 side and place the seal therein.

  In such a polymer electrolyte fuel cell stack according to the third embodiment, the same effects as those of the first embodiment and the second embodiment described above can be obtained.

  That is, in addition to performing sealing between the oxidant gas / cooling water manifolds 21 and 22 and the fuel gas manifolds 31 and 32 and the side surface of the fuel cell stack 10 with the first seal member, Between the seal surface and the side surfaces of the oxidant gas / cooling water manifolds 21 and 22, a seal groove is provided, a seal is disposed therein, and a second seal member is provided, so that a minute leak at the corner portion is prevented. Can be completely prevented.

  According to at least one embodiment described above, it is possible to prevent not only liquid and gas during operation but also minute oozing of water in the battery stack during stopped storage.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack, 11 ... Single cell battery 11, 12 ... Membrane electrode assembly (MEA), 13 ... Fuel separator, 13a ... Fuel gas flow path, 14 ... Oxidant / cooling water separator, 14a ... Oxidant gas Flow passage, 14b ... Cooling water flow passage, 21 ... Oxidant gas inlet / cooling water outlet manifold, 21a, 33c ... Seal groove, 22 ... Oxidant gas outlet / cooling water inlet manifold, 31 ... Fuel gas inlet manifold, 32 ... Fuel Gas outlet manifold, 41 ... polymer electrolyte membrane, 42a ... anode catalyst layer, 42b, 43b ... gas diffusion layer, 43a ... cathode catalyst layer, 51 ... edge seal material, 61, 62a, 62b, 62c ... manifold seal

Claims (5)

A membrane electrode assembly in which a solid polymer electrolyte membrane is sandwiched between first and second gas diffusion electrodes, a first separator having a fuel gas flow passage in contact with the first gas diffusion electrode, and the second A laminate comprising a plurality of unit cells each having a second separator having an oxidant gas flow passage in contact with the gas diffusion electrode;
The fuel gas flow passage of the laminate is disposed on a side surface where the fuel gas flow passage is open, a fuel gas external manifold communicating with the fuel gas flow passage, and the oxidant gas flow passage of the stack is disposed on a side surface of the stack, An oxidant gas external manifold communicating with the oxidant gas flow passage,
The fuel gas external manifold and the laminate are sealed by a fuel gas external manifold side first seal member, and the oxidant gas external manifold and the laminate are sealed by an oxidant gas external manifold side first seal member. The fuel cell stack is characterized in that the adjacent fuel gas external manifold and oxidant gas external manifold are sealed by a second seal member.   One of the peripheral ends of the adjacent fuel gas external manifold and oxidant gas external manifold extends so as to contact the side surface of the peripheral end of the other manifold, and a seal groove is formed in the extended portion. The fuel cell stack according to claim 1, wherein a sealing material is disposed in the sealing groove to constitute a second sealing member.   The peripheral end of one of the adjacent fuel gas external manifold and oxidant gas external manifold and the peripheral end of the other manifold are in contact with each other at a surface inclined with respect to the side surface of the laminate. 2. The fuel cell stack according to claim 1, wherein a seal groove is formed in one of the surfaces, and a seal material is disposed in the seal groove to constitute a second seal member.   The first seal member includes a seal groove formed on a surface of the peripheral end portion of the fuel gas external manifold and the oxidant gas external manifold in contact with the stacked body, and a seal material disposed in the seal groove. The fuel cell stack according to claim 2, wherein the fuel cell stack is configured.   The first seal member includes a seal groove formed on a surface of the laminate that is in contact with the peripheral end portions of the fuel gas external manifold and the oxidant gas external manifold, and a seal material disposed in the seal groove. The fuel cell stack according to claim 2 or 3, characterized by comprising:

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